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A* Episode 19, Page 1
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  A comic named after the wrong black holeOct 23, 2014 11:34 AM PDT | url | discuss | + share
 
Added 1 new A* page:There's a new print comic kind of named after the supermassive black hole at the center of our galaxy, Sagittarius A*! Or, it thought it was. As you can see in some really nice outer space illustrations by Frazer Irving in the second preview page of Annihilator #1 (click the "See what's inside" cover thumbnail in the upper right), that comic series takes its name from my own little webcomic's namesake, since, according to writer Grant Morrison, Sagittarius A* is also known as "The Great Annihilator."
 
Morrison is, however, mistaken. From what I find on Wikipedia, The Great Annihilator is not a name for the supermassive black hole A*, which is at the center of the galaxy, but for "a black hole of intermediate mass" "near" A*. This smaller black hole was spotted due to a highly energetic eruption almost exactly 14 years ago, according to one of their linked research papers, an article called (direct .pdf link) The Great Annihilator in the Central Region of the Galaxy by I.F. Mirabel, Service d'Astrophysique, CE-Saclay, France, which appeared in the December 1992 edition of the ESO's "Messenger" journal (hm, free subscription to a quarterly print publication—maybe I should subscribe! Then again, think of the trees); under the surprisingly poetic heading "1. The Sepulchral Silence of the Hypothetical Super-Massive Black Hole," Mirabel wrote

The French gamma-ray telescope SIGMA on board the Russian satellite GRANAT has recently found that the strongest source of 511 keV gammas is not at the dynamic centre of the Galaxy, but 50 arcminutes away from it. On October 13-14, 1990, SIGMA detected from this source a powerful annihilation burst, and we then realized that this object is the strongest compact annihilation source known in the Galaxy. Since it can fabricate 10 billion (1010) tons of positrons in just one second, it is now known under the name of the "Great Annihilator".

This wasn't where the term "the Great Annihilator" was first printed, though: Time had already used it in an article in their July 27, 1992 edition; hm, and a short article from the July 16, 1992 edition of Nature, by way of Physics Today, apparently read as follows:

THE GREAT ANNIHILATOR MAY BE A MICROQUASAR . The object 1E1740.7-2942 near the center of the Milky Way is an x-ray emitter and also the brightest source of positrons in the sky; the positrons reveal themselves through their collisions with electrons, resulting in the characteristic gamma radiation at 511 keV and hence the name Great Annihilator. A team of French astronomers, using the Very Large Array in New Mexico, has now studied the object at radio wavelengths and found that it exhibits radio-emitting jets whose behavior is synchronous with the variable gamma source. All of this suggests to the French astronomers that the core of 1E1740.7-2942 resembles a sort of mini-quasar. (Nature, 16 July 1992.)

Indeed, Mirabel—who I suppose was likely to have been one of those "French astronomers—in the afore-mentioned article that would appear that December, wrote, first describing A*

For two decades gamma-ray astronomers observing the galactic centre region with many balloon and satellite-borne instruments have been reporting intermittent radiation from the annihilation of positrons with electrons. Positrons are electrons of positive charge that annihilate when they meet ordinary matter, producing pairs of photons of 511 keV, the rest-mass energy of the annihilated particules. The sporadic appearance of this type of gamma radiation in the central region of our Galaxy indicated the existence of a compact object (or objects) capable of fabricating enormous quantities of positrons in short periods of time. The poor angular resolution of the detectors used until recently gave wide latitude to the belief that the mysterious compact source of positrons could be a black hole of several million solar masses residing at the dynamic centre of the Galaxy.

and then the Great Annihilator

The Great Annihilator may be a black hole of stellar mass. In its standard state, the X-ray spectrum resembles that of the stellar-mass black-hole candidate Cygnus X-i, both in shape and intrinsic luminosity. Furthermore, dynamic studies of sources detected by SIGMA beyond 100 keV show that they are likely to be binary systems with gravitationally collapsed objects having masses between 3 and a few tens of solar masses.

and would go on to hypothesize that

the unusual properties of the Great Annihilator are the result of two conditions, each of which has a small probability of being satisfied: first, that the object is located within a dense cloud, and second, that it has a relativeIy small velocity with respect to that cloud. Our calculations show that only one among the -40,000 massive remnants within 200 pc from the centre of the Galaxy would satisfy the conditions required to produce a substantial accretion luminosity without a binary companion. Therefore, it is not surprising that despite the large amount of compact objects in the central region of the Galaxy, there is only one Great Annihilator.

The Great Annihilator was also found to be emitting radioactive particle jets three light years long—there's a photo of that in the pdf of the article, along with an X-ray reading from the Great Annihilator, with A* marked (and silent) nearby.
 
So, in fact, the Great Annihilator could be somewhere in the neighborhood of 400,000 times or more less massive than A* (which has since been found to be closer to 4 million solar masses than Mirabel's proposed 2)—but it happened to be sucking its way through a dense cloud of material and thus emitting high energy gamma rays at the time, while A* wasn't. A*, perhaps, is on the scale of not needing any fancy title to enlarge itself. However, if you do for instance want to write a webcomic based around The Great Annihilator rather than around A*, I see that both the thegreatannihilator.com and greatannihilator.com domain names are available. : D
 
 
 
 
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